Systems and methods for controlling an engine based on aftertreatment system characteristics

ABSTRACT

Systems and apparatuses include an apparatus including an aftertreatment system control circuit structured to receive a signal indicative of an exhaust gas characteristic from a sensor, determine an aftertreatment system characteristic based on the exhaust gas characteristic, determine an acceptable input value responsive to the aftertreatment system characteristic, and control at least one of a fuel system actuator and an air handling actuator to achieve or substantially achieve the acceptable input value.

TECHNICAL FIELD

The present disclosure relates to aftertreatment systems. Moreparticularly, the present disclosure relates to systems and methods forcontrolling engine operating parameters response to one or more exhaustaftertreatment system characteristics.

BACKGROUND

Exhaust aftertreatment systems are designed to reduce emissions ofharmful exhaust gases produced by an engine. Exhaust aftertreatmentsystems may include a selective catalyst reduction (SCR) system, anexhaust gas recirculation (EGR) system, and/or various other systemcomponents intended to reduce emissions (e.g., reduce particulatematter, NOx, etc.) to less environmentally harmful emissions.

SUMMARY

One embodiment relates to an apparatus that includes an aftertreatmentsystem control circuit structured to receive a signal indicative of anexhaust gas characteristic from a sensor, determine an aftertreatmentsystem characteristic based on the exhaust gas characteristic, determinean acceptable input value responsive to the aftertreatment systemcharacteristic, and control at least one of a fuel system actuator andan air handling actuator to achieve or substantially achieve theacceptable input value.

Another embodiment relates to a system that includes a sensor structuredto provide a sensor signal indicative of an exhaust gas characteristic,an aftertreatment system control circuit, and an engine control circuit.The aftertreatment system control circuit is structured to receive thesensor signal, determine an aftertreatment system characteristic as afunction of the exhaust gas characteristic, determine an acceptableinput value as a function of the aftertreatment system characteristic,and send a command signal indicative of the acceptable input value. Theengine control circuit is structured to receive the command signal, andto control at least one of a fuel system and an air handling actuator toachieve or substantially achieve the acceptable input value.

Another embodiment relates to a method that includes receiving a signalindicative of an exhaust gas characteristic from an aftertreatmentsensor by an aftertreatment system control circuit. An aftertreatmentsystem characteristic is determined by the aftertreatment system controlcircuit as a function of the exhaust gas characteristic. An acceptableinput value is determined by the aftertreatment system control circuitas a function of the aftertreatment system characteristic, and theacceptable input value is communicated to an engine control circuit.Then at least one of a fuel system and an air handling actuator iscontrolled by the engine control circuit to achieve the acceptable inputvalue.

These and other features, together with the organization and manner ofoperation thereof, will become apparent from the following detaileddescription when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of an engine and an aftertreatment system,according to an example embodiment.

FIG. 2 is a schematic diagram of an aftertreatment system controllerused with the aftertreatment system of FIG. 1, according to an exampleembodiment.

FIG. 3 is a flow chart illustrating a method of controlling the engineof FIG. 1 using the aftertreatment system controller of FIG. 2,according to an example embodiment.

FIG. 4 is a flow chart illustrating a method of controlling the engineof FIG. 1 using the aftertreatment system controller of FIG. 2,according to an example embodiment.

FIG. 5 is a flow chart illustrating a method of generating faults usingthe aftertreatment system controller of FIG. 2, according to an exampleembodiment.

DETAILED DESCRIPTION

Following below are more detailed descriptions of various conceptsrelated to, and implementations of, methods, apparatuses, and systemsfor model based catalyst diagnostics. The various concepts introducedabove and discussed in greater detail below may be implemented in anynumber of ways, as the concepts described are not limited to anyparticular manner of implementation. Examples of specificimplementations and applications are provided primarily for illustrativepurposes.

Referring the Figures generally, the various embodiments disclosedherein relate to systems, apparatuses, and methods for an aftertreatmentsystem controller to communicate one or more aftertreatment system inputvalues or conditions to an engine controller to control an engine basedon these one or more aftertreatment system input conditions in order toachieve a desired operating characteristic of the aftertreatment system.The aftertreatment system controller receives information from variousaftertreatment sensors (e.g., virtual sensors or real sensors) anddetermines in real, or substantially real time the capacity orcapabilities of the aftertreatment system. For example, the capabilitiesmay include a NOx emissions amount being above or below a predefinedthreshold value, an indication of an ammonia slip amount being above athreshold value, etc. Based on these determined capabilities, theaftertreatment system controller can control or facilitate control ofone or more engine operating conditions in order to impact/affectvarious characteristics of the exhaust aftertreatment system to meet orsubstantially meet one or more predefined desired characteristics of theaftertreatment system (such as, ensuring or substantially ensuring NOxemissions are below the threshold value, etc.). This control schemeprovides an improved usage efficiency of the overall aftertreatmentsystem and provides benefits including, but not limited to, feweronboard diagnostic (OBD) faults, fewer OBD false faults (e.g.,identifying a healthy or properly functioning system or component asfaulty), a dynamic relationship between engine operating conditions andaftertreatment system operating conditions, improved fuel efficiency,the possibility of reduced catalyst size and system size, improvedemissions reduction over the life of the aftertreatment system, and thepotential to reduce the size/influence of or eliminate entirely anammonia oxidation catalyst (AMOX) system from the aftertreatment system.

As shown in FIG. 1, an engine system 20 includes an air handling systemactuator 24, an engine 26 including a combustion chamber, and a fuelsystem actuator 28. In one configuration, the engine system 20 can be aninternal combustion engine such as a spark-ignition engine fueled bygasoline, natural gas, ethanol, propane, or another fuel suitable forspark-ignition. In the example shown, the engine system 20 is acompression-ignition engine fueled by diesel, or another fuel suitablefor compression-ignition. The engine 26 can include a combustion chamberand an exhaust port or manifold that couples to the engine exhaust pipeto contain the engine exhaust gases. Many designs and arrangements ofengines may be used with the embodiments described herein and the enginesystem 20 shown and described are to be construed as a non-limitingexample.

The engine system 20 may be implemented in a variety of applications.For example, in one embodiment, the engine system 20 is implemented in avehicle. The vehicle may include, but is not limited to, an on-road oran off-road vehicle including, but not limited to, line-haul trucks,mid-range trucks (e.g., pick-up truck), cars (e.g., sedans, hatchbacks,coupes, etc.), buses, vans, refuse vehicles, delivery trucks, and anyother type of vehicle. In another configuration, the engine system 20 isimplemented in another type of engine-driven equipment such as miningequipment, a power generator, and marine equipment.

In the example shown, the air handling system actuator 24 is positionedin an air flow path upstream of the combustion chamber and affects theflow of air through the engine system 20. In other embodiments, the airhandling system actuator 24 is positioned in an airflow path downstreamof the combustion chamber and affects the flow of air though the enginesystem 20. In some embodiments, the air handling system actuator 24 is avalve within a turbocharger unit. In some embodiments, the air handlingsystem actuator 24 is a valve within a supercharger unit or anothercompressor that provides pressurized air to the combustion chamber. Insome embodiments, the air handling system actuator 24 is a motor, acontroller, a valve, a vent, a variable geometry turbo charger (VGT)actuator, an automatic voltage regulator (AVR) valve, an enginethrottle, an exhaust throttle an exhaust gas recirculation (EGR) valve,or an engine brake. In some embodiments the air handling system actuator24 is a controller or control circuit that affects operation of an airhandling system or component thereof. Thus, the air handling systemactuator 24 can be any component of the engine system 20 that affectsthe flow of air into or out of the combustion chamber to affect theoperating characteristics of the engine system 20.

The fuel system actuator 28 is positioned in a fuel flow path upstreamof the combustion chamber and affects the flow of fuel to the combustionchamber. Accordingly, the fuel system actuator 28 may include, but isnot limited to, a fuel injector, a rail valve, a fuel pump, a meteringvalve, a controller or control circuit, another component of a fuelsystem that affects the flow of fuel to the combustion chamber, and/or acombination thereof.

An aftertreatment system 32 is coupled to the engine 20 to receiveexhaust gases from the engine system 20 and treat the exhaust gases toreduce emissions of harmful exhaust gas constituents (e.g., reduce COemissions, reduce NOx emissions, reduce particulate matter emissions,reduce unburnt hydrocarbon emissions, etc.). As shown, theaftertreatment system 32 includes a selective catalyst reduction (SCR)system 36 and an exhaust gas recirculation (EGR) system 40. However, inother embodiments, the aftertreatment system 32 includes a three-waycatalyst, a two-way catalyst, a diesel particulate filter (DPF), adiesel oxidative catalyst (DOC), an AMOx catalyst, and/or any otheraftertreatment system component as desired. Thus, the particularcomponents of the aftertreatment system 32 are discussed as non-limitingexamples s the systems, apparatuses, and methods described herein may bepracticed with other aftertreatment components. In this regard, those ofordinary skill in the art will readily recognize and appreciate the highconfigurability of the aftertreatment system 32 (e.g., as to the type ofcomponents includes, the relative locations of those components, etc.)with all such variations intended to fall within the spirit and scope ofthe present disclosure.

An exhaust system 44 is fluidly coupled to the aftertreatment system 32to receive the treated exhaust gas from the aftertreatment system 32.The exhaust system 44 can include a muffler, a particulate filter, orother components as desired.

A control system 48 is coupled to at least one engine system 20 (or acomponent therein), the aftertreatment system 32, and the exhaust system44. The control system 48 controls operation of the engine system 20 andthe aftertreatment system 32. The control system 48 includes an enginecontrol unit (ECU) 52, an aftertreatment system controller 56, an engineout temperature sensor 60, an engine out nitrogen oxides (NOx) sensor64, an ammonia (NH3) slip sensor 68, and an aftertreatment system outtemperature sensor 72. The ECU 52 is in communication with theaftertreatment system controller 56 and controls operation of the airhandling system actuator 24 and the fuel system actuator 28. The ECU 52may also be in communication with various sensors and othersystems/components of the engine system 20 to affect and controloperating conditions and parameters of the engine system 20.

The engine out temperature sensor 60 is positioned to sense/acquire dataindicative of a temperature of exhaust gas leaving the engine system 20before the exhaust gas enters the aftertreatment system 32. In thisregard, the engine out temperature sensor 60 provides an engine outtemperature signal to the aftertreatment system controller 56 that isindicative of the temperature of the exhaust gas leaving the enginesystem 20.

The engine out NOx sensor 64 is positioned to sense/acquire dataindicative of a NOx level or amount in the exhaust gas leaving theengine system 20 before the exhaust gas enters the aftertreatment system32. The engine out NOx sensor 64 provides an engine out NOx signal tothe aftertreatment system controller 56 that is indicative of the NOxlevel of the exhaust gas leaving the engine system 20.

The NH3 slip sensor 68 is positioned to sense/acquire data indicative ofa NH3 level leaving the aftertreatment system 32. The NH3 slip sensor 68provides an ammonia slip signal to the aftertreatment system controller56 that is indicative of the NH3 level of the exhaust gas leaving theaftertreatment system 32. In other configurations, the NH3 slip sensormay be omitted from the aftertreatment system. In this configuration,NH3 slip could be detected via an NH3 sensor, some other sensor that iscross sensitive to NH3, or via some sort of signal processing orembedded catalyst model.

The aftertreatment system out temperature sensor 72 is positioned tosense/acquire data indicative of a temperature of exhaust gas leavingthe aftertreatment system 32. The aftertreatment system out temperaturesensor 72 provides an aftertreatment system out temperature signal tothe aftertreatment system controller 56 that is indicative of thetemperature of the exhaust gas leaving the aftertreatment system 32.

The sensors discussed above are only exemplary. The position, type, andnumber of sensors may be changed in other embodiments. For example, theammonia slip may be detected by a virtual sensor (e.g., a calculationbased on NH3 dosing rates and NOx sensor readings). As another example,a pressure sensor or fluid flow sensor may be implemented downstream ofthe engine 26.

As shown in FIG. 2, a schematic diagram of the aftertreatment systemcontroller 56 is depicted according to an example embodiment. Thecontroller 56 includes a processing circuit 76 having a processor 80 anda memory device 84, a control system 88, and a communications interface92. The control system 88 includes a sensor circuit 96, a gascharacteristic circuit 100, a system characteristic circuit 104, acomparison circuit 108, an acceptable value circuit 112, and an enginecontrol circuit 116. The aftertreatment system controller 56 isstructured to communicate with the engine out temperature sensor 60, theengine out NOx sensor 64, the NH3 slip sensor 68, and the aftertreatmentsystem out temperature sensor 72 and to provide catalyst input values tothe ECU 52 so that the engine system 20 is operated to meet orsubstantially meet a desired operating characteristic of theaftertreatment system.

In one configuration, the control system 88 is embodied as machine orcomputer-readable media that is executable by a processor, such asprocessor 80. Amongst other uses, the machine-readable media facilitatesperformance of certain operations to enable reception and transmissionof data. For example, the machine-readable media may provide aninstruction (e.g., command, etc.) to, e.g., acquire data. In thisregard, the machine-readable media may include programmable logic thatdefines the frequency of acquisition of the data (or, transmission ofthe data). The computer readable media may include code, which may bewritten in any programming language including, but not limited to, Javaor the like and any conventional procedural programming languages, suchas the “C” programming language or similar programming languages. Thecomputer readable program code may be executed on one processor ormultiple remote processors. In some embodiments, multiple remoteprocessors may be connected to each other through any type of network(e.g., CAN bus, etc.).

In another configuration, the control system 88 is embodied as hardwareunits, such as electronic control units. As such, the control system 88may be embodied as one or more circuitry components including, but notlimited to, processing circuitry, network interfaces, peripheraldevices, input devices, output devices, sensors, etc. In someembodiments, the control system 88 may take the form of one or moreanalog circuits, electronic circuits (e.g., integrated circuits (IC),discrete circuits, system on a chip (SOCs) circuits, microcontrollers,etc.), telecommunication circuits, hybrid circuits, and any other typeof “circuit.” In this regard, the control system 88 may include any typeof component for accomplishing or facilitating achievement of theoperations described herein. For example, a circuit may include one ormore transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR,etc.), resistors, multiplexers, registers, capacitors, inductors,diodes, wiring, and so on). The control system 88 may also includeprogrammable hardware devices such as field programmable gate arrays,programmable array logic, programmable logic devices or the like. Thecontrol system 88 may include one or more memory devices for storinginstructions that are executable by the processor(s) of the controlsystem 88 or the processor 80. The one or more memory devices andprocessor(s) may have the same definition as provided below with respectto the memory device 84 and processor 80. In this hardware unitconfiguration, the control system 88 may be geographically dispersedthroughout separate locations in the engine system 20, theaftertreatment system 32, or another component of an overall system suchas a vehicle. Alternatively, and as shown, the control system 88 may beembodied in or within a single unit/housing, which is shown as theaftertreatment system controller 56.

In the example shown, the aftertreatment system controller 56 includesthe processing circuit 76 having the processor 80 and the memory 84. Theprocessing circuit 76 may be structured or configured to execute orimplement the instructions, commands, and/or control processes describedherein with respect to the control system 88. The depicted configurationrepresents the aforementioned arrangement where the control system 88 isembodied as machine or computer-readable media. However, as mentionedabove, this illustration is not meant to be limiting as the presentdisclosure contemplates other embodiments such as the aforementionedembodiment where the control system 88, or at least one circuit of thecontrol system 88, is configured as a hardware unit. All suchcombinations and variations are intended to fall within the scope of thepresent disclosure.

The processor 80 may be implemented as one or more general-purposeprocessor, an application specific integrated circuit (ASIC), one ormore field programmable gate arrays (FPGAs), a digital signal processor(DSP), a group of processing components, or other suitable electronicprocessing components. In some embodiments, the one or more processorsmay be shared by multiple circuits (e.g., the circuits of the controlsystem 88 may comprise or otherwise share the same processor which, insome example embodiments, may execute instructions stored, or otherwiseaccessed, via different areas of memory). Alternatively or additionally,the one or more processors may be structured to perform or otherwiseexecute certain operations independent of one or more co-processors. Inother example embodiments, two or more processors may be coupled via abus to enable independent, parallel, pipelined, or multi-threadedinstruction execution. All such variations are intended to fall withinthe scope of the present disclosure.

The memory 84 (e.g., RAM, ROM, Flash Memory, hard disk storage, etc.)may store data and/or computer code for facilitating the variousprocesses described herein. The memory 84 may be communicably connectedto the processor 80 to provide computer code or instructions to theprocessor 80 for executing at least some of the processes describedherein. Moreover, the memory 84 may be or include tangible,non-transient volatile memory or non-volatile memory. Accordingly, thememory 84 may include database components, object code components,script components, or any other type of information structure forsupporting the various activities and information structures describedherein.

The communication interface 92 is structured to provide and enablecommunications between and among the processing circuit 76, the controlsystem 88, the engine out temperature sensor 60, the engine out NOxsensor 64, the NH3 slip sensor 68, and the aftertreatment system outtemperature sensor 72, and the ECU 52. In some embodiments, thecommunication interface 92 also communicates directly with the airhandling system actuator 24, and the fuel system actuator 28.

The sensor circuit 96 is structured to communicate with the engine outtemperature sensor 60, the engine out NOx sensor 64, the NH3 slip sensor68, and the aftertreatment system out temperature sensor 72 (and anyother sensors included in the system) via the communication interface92. The sensor circuit 96 is structured to receive the engine outtemperature signal from the engine out temperature sensor 60 anddetermine the temperature or an approximate temperature of the exhaustgas leaving the engine system 20. The sensor circuit 96 is structured toreceive the engine out NOx signal from the engine out NOx sensor 64 anddetermine the NOx level or an approximate NOx level, amount, percentage,etc. of the exhaust gas leaving the engine system 20. The sensor circuit96 is structured to receive the ammonia slip signal from the NH3 slipsensor 68 and determine the NH3 level of the exhaust gas leaving theaftertreatment system 32. The sensor circuit 96 is structured to receivethe aftertreatment system out temperature signal from the aftertreatmentsystem out temperature sensor 72 and determine the temperature of theexhaust gas leaving the aftertreatment system 32. In some embodiments,the sensor circuit 96 communicates with other sensors to determine othercharacteristics. It should be understood that determined, measured, orotherwise acquired values are each examples of sensor data that can beused by the aftertreatment system controller 56. Other sensor data mayalso be used. For example, other temperatures, NOx levels, NH3 levels,or other values may be sensed and determined and subsequently used tocontrol the engine system 20 or the aftertreatment system 32.

The gas characteristic circuit 100 is structured to receive the sensordata from the sensor circuit 96 and determine a gas characteristic. Insome embodiments, the gas characteristic includes a NOx level measuredor determined by the NOx sensor 64, or another sensor. In someembodiments, the gas characteristic is a NOx level present in a part ofthe aftertreatment system 32 other than at the point measured by theengine out NOx sensor 64 (e.g., upstream of the exhaust system 44 if theNOx sensor 64 is positioned immediately downstream of the engine system20, etc.). The gas characteristic circuit 100 may use the sensor data todetermine an aftertreatment system NOx out level, an oxygen level ofexhaust gas entering the aftertreatment system 32, a NOx reduction(deNOx) rate, and a variety of other gas characteristics that may beused to aid in the control of the aftertreatment system 32 and enginesystem 20.

The system characteristic circuit 104 is structured to receive the gascharacteristic from the gas characteristic circuit 100 to determine asystem characteristic. The system characteristic may include, but is notlimited to, a deNox efficiency, a future or predicted deNox efficiency,a system out NOx value, an exhaust gas flow rate, an exhaust gastemperature, an NH3 storage value, a urea dosing rate, a NH3 slip rate,a future or predicted NH3 slip rate, a NH3 slip value, and/or a futureor predicted NH3 slip value. In some embodiments, other systemcharacteristics may also be determined. For example, a catalyst oxygenstorage capacity may be determined.

The comparison circuit 108 is structured to communicate with the systemcharacteristic circuit 104 and the memory 84 to compare the systemcharacteristic to a predetermined threshold stored in the memory 84. Thepredetermined threshold may be a value, a range of values, etc.indicative of an acceptable operating characteristic for the system (orvice versa, an unacceptable operating characteristic for the system).The comparison circuit 108 is structured to determine an offset or adifferential between the system characteristic and the predeterminedthreshold.

The acceptable value circuit 112 is structured to receive the offsetfrom the comparison circuit 108 and determine an acceptable input value.The acceptable input value defines a desired condition of exhaust gasexiting the engine system 20 and entering the aftertreatment system 32.In some embodiments, the acceptable input value includes a range ofvalues that are acceptable to the aftertreatment system controller 56.For example, the acceptable input value may include an engine outtemperature or a range of engine out temperatures, or an engine out NOxvalue or a range of engine out NOx values, an engine out particulatematter amount, etc.

The engine control circuit 116 is structured to receive the acceptableinput range from the acceptable value circuit 112 and communicate withthe ECU 52 via the communication interface 92. The engine controlcircuit 116 and the ECU 52 are structured to control operation of theair handling system actuator 24, engine 26, and/or the fuel systemactuator 28 in order to realize/achieve or substantially achieve theacceptable input value.

In this regard, the air handling system actuator 24 is controlled toaffect the engine system 20 operation and combustion characteristicssuch that the acceptable input value is realized. For example, aturbocharger valve or operation may be altered, an EGR valve may beopened or closed, the throttle position or values may be altered, and/orthe engine brake may be engaged or disengaged.

In another embodiment, the fuel system actuator 28 is controlled toaffect the engine system 20 operation and combustion characteristicssuch that the acceptable input value is realized. For example, aquantity of fuel provided to the combustion chamber may be altered, thetiming of fuel injection or the pressure of fuel injection may bealtered, and/or ignition timing may be altered.

In another embodiment, the engine 26 is controlled or managed to affectthe combustion characteristics such that the acceptable input value isrealized or achieved. Control of the engine 26 may be within theconfines of operation of the engine 26 to, e.g., meet a vehicle speedrequirement, a torque requirement, etc. Thus, while the engine 26 may bemanipulated to achieve the acceptable input value, a boundary conditionor regulation may be implanted that confines the acceptable use of theengine 26. That said, control of the engine 26 can include controllingan engine speed.

In yet another embodiment, a combination of the fuel system actuator 28,engine 26, and the air handling system actuator 24 is controlled ormanaged to achieve or substantially achieve the acceptable input value.

Utilizing the aftertreatment system controller 56, the engine system 20can be operated to improve fuel economy. In other words, theaftertreatment system 32 can be operated near to a maximum capacity ormaximum emissions reduction enabling the engine system 20 to run moreefficiently.

As shown in FIG. 3, a method 120 of operating the engine system 20includes determining an acceptable input value with the control system88 based on sensor data at process 124. The acceptable input value mayinclude a range of values that the aftertreatment system controller 56determines are acceptable to produce a desired outcome or systemcharacteristic. For example, the aftertreatment system controller 56 maydetermine that a deNOx efficiency is greater than a threshold value, andprovide an acceptable input value or range that allows the engine system20 to operate at a higher fuel efficiency and produce a larger engineout NOx value. In one example, the deNOx efficiency threshold value isabout or approximately ninety percent (90%) (e.g., plus-or-minus twopercent). In some other embodiments, the deNOx efficiency thresholdvalue is between about or approximately ninety percent (90%) and aboutninety nine percent (99%).

At process 128, the acceptable input value is communicated via thecommunications interface 92 to the ECU 52. The ECU 52 may operate theengine system 20 in view of the acceptable input value. At process 132,the ECU 52 adjusts operation of the air handling system actuator 24and/or the fuel system actuator 28 in order to realize the acceptableinput value. Once the operation of the engine system 20 is adjusted, theaftertreatment system controller 56 continues to monitor the sensor dataand provide feedback to the ECU 52 in order to control the engine system20 to operate within the acceptable input value or range. The method 120provides engine control based at least in part on exhaust gascharacteristics and is directed by the aftertreatment system controller56. In a typical system, the ECU operates the engine independently, andthe aftertreatment system must be sized and adapted to accommodatewhatever the engine produces. The method 120 allows the engine system 20to be operated with an improved fuel economy because the aftertreatmentsystem 32 is being used more effectively. Additionally, the method 120allows the size and/or overall capacity of the aftertreatment system 32to be reduced because the engine system 20 is controlled to operatewithin the available capacity of the aftertreatment system 32, and notthe other way around.

As shown in FIG. 4, a method 136 of operating the engine system 20includes determining one or more exhaust gas characteristics with thegas characteristic circuit 100 at process 140. The exhaust gascharacteristic may include a NOx level, a NH3 slip amount or value, atemperature, or another characteristic.

At process 144, the system characteristic circuit 104 determines one ormore system characteristics based on the exhaust gas characteristicsdetermined in process 140. In some embodiments, the systemcharacteristics include a deNOx efficiency, a NH3 slip, a predicted NH3slip, and/or a ratio of NO and NO2. In some embodiments, the systemcharacteristics include temperatures at specific positions in theaftertreatment system 32, exhaust gas flow rates, actual or calculatedNOx values, actual or calculated NH3 values, actual or calculated oxygenvalues, and/or other characteristics.

At process 148, the deNOx efficiency is compared to a predetermineddeNOx threshold by the comparison circuit 108. In general, the deNOxefficiency increases as engine out temperature increases. In someembodiments, the deNOx threshold is about ninety-five percent (95%). Insome embodiments, the deNOX threshold is a range between about ninetypercent and about ninety-five percent (90-95%).

If the deNOx efficiency is less than (or at or less than) the deNOxthreshold, then the method 136 progresses to process 152 and theacceptable value circuit 112 determines an acceptable input value inresponse to the comparison at process 148. The acceptable input value isthen communicated to the ECU 52 by the engine control circuit 116. Atprocess 152, the acceptable input value is an increased engine outtemperature and/or a lower engine out NOx value.

At process 156, the ECU 52 receives the acceptable input value andcontrols the air handling system actuator 24 and/or the fuel systemactuator 28 in order to achieve or realize the acceptable input value.As discussed above, the ECU 52 may affect fuel quantity, pressure,timing, etc. and/or air flow via a turbocharger, an EGR valve, athrottle, an exhaust throttle, or an engine break. In some embodiments,other actuators or systems may be used to affect the combustioncharacteristics of the engine system 20 such that the acceptable inputvalue and/or range is achieved.

If the aftertreatment system controller 56 determines at process 148that the deNOx efficiency is not less than the deNOx threshold, then themethod proceeds to process 160 and the NH3 slip is compared to apredetermined NH3 slip threshold by the comparison circuit 108. If theNH3 slip is greater than the NH3 slip threshold, the acceptable valuecircuit 112 determines an acceptable input value and the engine controlcircuit 116 communicates with the ECU 52 at step 164. The acceptableinput value determined at step 164 is a decreased engine out temperatureand/or a higher engine out NOx value. In some embodiments, the NH3 slipthreshold is about or approximately twenty five (25) parts per million(ppm). In some other embodiments, the NH3 slip threshold is betweenabout or approximately ten (10) ppm and about fifty (50) ppm. It shouldbe understood that the terms “about” or “approximately” are intended tohave their ordinary meaning in the art when quantifying PPM of NH3 slip.

The acceptable input value determined at process 164 is received by theECU 52 at process 156, and the ECU 52 controls the air handling systemactuator 24, engine 26, and/or the fuel system actuator 28 in order toachieve or realize the acceptable input value.

If the aftertreatment system controller 56 determines at process 160that the NH3 slip is not greater than the NH3 slip threshold, then themethod proceeds to process 168 and the predicted NH3 slip is compared tothe predetermined NH3 slip threshold by the comparison circuit 108. Insome embodiments, the predicted NH3 slip is determined by the systemcharacteristic circuit 104 using urea dosing data, temperature data, andNOx data. If the predicted NH3 slip is greater than the NH3 slipthreshold, the acceptable value circuit 112 determines an acceptableinput value at step 164 including a decreased engine out temperatureand/or a higher engine out NOx value, and ECU 52 receives the acceptableinput value at step 156. The ECU 52 then controls the air handlingsystem actuator 24, engine 26, and/or the fuel system actuator 28 atstep 156 to achieve the acceptable input value.

If the aftertreatment system controller 56 determines at process 168that the predicted NH3 slip is not greater than the NH3 slip threshold,then the method proceeds to process 172 and the deNOx efficiency iscompared to the deNOx efficiency threshold by the comparison circuit108. If the deNOx efficiency is greater than the deNOx efficiencythreshold, the acceptable value circuit 112 determines an acceptableinput value at step 164 including a decreased engine out temperatureand/or a higher engine out NOx value, and ECU 52 receives the acceptableinput value at step 156. The ECU 52 then controls the air handlingsystem actuator 24 and/or the fuel system actuator 28 at step 156 toachieve the acceptable input value. If the deNOx efficiency is notgreater than the deNOx efficiency threshold, the method returns toprocess 140 and continues to monitor the aftertreatment system 32 viathe sensor data.

As shown in FIG. 5, the aftertreatment system controller 56 alsoprovides an improved fault detection system. In typical aftertreatmentsystems, situations can arise where a false fault is generated becauseconditions occur that were not tested for during production. Theaftertreatment system controller 56 is able to utilize the determinedacceptable input values to monitor the engine system 20 andaftertreatment system 32. By determining faults based on the acceptableinput value, the aftertreatment system controller 56 can account forvariability in system components and operating conditions. A method 176of determining faults includes monitoring the acceptable input valuesgenerated by the acceptable value circuit 112 at process 180. In someembodiments, the acceptable input values are generated using the method136 at processes 152 and/or 164.

At process 184, the acceptable input value is compared to apredetermined threshold criterion. In some embodiments, the thresholdcriterion is an engine out temperature range. If the engine outtemperature determined by the gas characteristic circuit 100 does notfall within, or does not meet the threshold criterion, then a fault codeis generated at process 188. In some embodiments, the thresholdcriterion is a NH3 slip and if the NH3 slip determined by the gascharacteristic circuit 100 does not fall within, or does not meet thethreshold criterion, then a fault code is generated at process 188.Other characteristics and acceptable input values are contemplated andmay be used both for control of the engine system 20 and for faultdetection.

As discussed above, the aftertreatment system controller 56 and theoverall system described herein can provide for the reduction in size oreven, in some instances, the elimination of particular aftertreatmentsystem components. For example, a system as described above may becapable of significantly reducing the size of an ammonia oxidation(AMOX) catalyst. Current systems must include AMOX catalysts that arelarger than required in order to account for aging and the resultantreduction is effectiveness. The aftertreatment system controller 56 isstructured to control the engine system 20 such that ammonia in the AMOXcatalyst is always or mostly always used/burned and NH3 slip isminimized. For example, if the AMOX catalyst has degraded over time, theengine system 20 is controlled to function within the limits oroperating parameters of the current condition of the AMOX catalyst.

Similarly, the AMOX catalyst may be entirely eliminated if the enginesystem 20 is controlled by the aftertreatment system controller 56. Bymonitoring the NH3 slip and predicted NH3 slip, the aftertreatmentsystem controller 56 can adjust the engine system 20 operatingparameters to produce more NOx and burn the slipping NH3. The reductionin the size and complexity of the AMOX catalyst can improve reliability,production costs, and maintenance costs of the aftertreatment system.

It should be understood that no claim element herein is to be construedunder the provisions of 35 U.S.C. § 112(f), unless the element isexpressly recited using the phrase “means for.”

For the purpose of this disclosure, the term “coupled” means the joiningor linking of two members directly or indirectly to one another. Suchjoining may be stationary or moveable in nature. For example, apropeller shaft of an engine “coupled” to a transmission represents amoveable coupling. Such joining may be achieved with the two members orthe two members and any additional intermediate members. For example,circuit A communicably “coupled” to circuit B may signify that thecircuit A communicates directly with circuit B (i.e., no intermediary)or communicates indirectly with circuit B (e.g., through one or moreintermediaries).

While various circuits with particular functionality are shown in FIGS.1 and 2, it should be understood that the ECU 52 and/or theaftertreatment system controller 56 may include any number of circuitsfor completing the functions described herein. For example, theactivities and functionalities of the sensor circuit 96, the gascharacteristic circuit 100, the system characteristic circuit 104, thecomparison circuit 108, the acceptable value circuit 112, and/or theengine control circuit 116 may be combined in multiple circuits or as asingle circuit. Additional circuits with additional functionality mayalso be included. Further, it should be understood that the ECU 52and/or the aftertreatment system controller 56 may further control otheractivity beyond the scope of the present disclosure.

As mentioned above and in one configuration, the “circuits” may beimplemented in machine-readable medium for execution by various types ofprocessors, such as processor 80 of FIG. 2. An identified circuit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions, which may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified circuit need not be physically locatedtogether, but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the circuitand achieve the stated purpose for the circuit. Indeed, a circuit ofcomputer readable program code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data, values, inputs, may be embodied in anysuitable form and organized within any suitable type of data structure.The operational data may be collected as a single data set, or may bedistributed over different locations including over different storagedevices, and may exist, at least partially, merely as electronic signalson a system or network.

While the term “processor” is briefly defined above, it should beunderstood that the term “processor” and “processing circuit” are meantto be broadly interpreted. In this regard and as mentioned above, the“processor” may be implemented as one or more general-purposeprocessors, application specific integrated circuits (ASICs), fieldprogrammable gate arrays (FPGAs), digital signal processors (DSPs), orother suitable electronic data processing components structured toexecute instructions provided by memory. The one or more processors maytake the form of a single core processor, multi-core processor (e.g., adual core processor, triple core processor, quad core processor, etc.),microprocessor, etc. In some embodiments, the one or more processors maybe external to the apparatus, for example the one or more processors maybe a remote processor (e.g., a cloud based processor).

It should be noted that although the diagrams herein may show a specificorder and composition of method steps, it is understood that the orderof these steps may differ from what is depicted. For example, two ormore steps may be performed concurrently or with partial concurrence.Also, some method steps that are performed as discrete steps may becombined, steps being performed as a combined step may be separated intodiscrete steps, the sequence of certain processes may be reversed orotherwise varied, and the nature or number of discrete processes may bealtered or varied. The order or sequence of any element or apparatus maybe varied or substituted according to alternative embodiments.Accordingly, all such modifications are intended to be included withinthe scope of the present disclosure as defined in the appended claims.Such variations will depend on the machine-readable media and hardwaresystems chosen and on designer choice. It is understood that all suchvariations are within the scope of the disclosure.

The foregoing description of embodiments has been presented for purposesof illustration and description. It is not intended to be exhaustive orto limit the disclosure to the precise form disclosed, and modificationsand variations are possible in light of the above teachings or may beacquired from this disclosure. The embodiments were chosen and describedin order to explain the principals of the disclosure and its practicalapplication to enable one skilled in the art to utilize the variousembodiments and with various modifications as are suited to theparticular use contemplated. Other substitutions, modifications, changesand omissions may be made in the design, operating conditions andarrangement of the embodiments without departing from the scope of thepresent disclosure as expressed in the appended claims.

Accordingly, the present disclosure may be embodied in other specificforms without departing from its spirit or essential characteristics.The described embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the disclosure is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. An apparatus comprising: an aftertreatment systemcontrol circuit structured to: receive a signal indicative of an exhaustgas characteristic from a sensor, determine an aftertreatment systemcharacteristic based on the exhaust gas characteristic, determine anacceptable input value responsive to the aftertreatment systemcharacteristic, and control at least one of a fuel system actuator andan air handling actuator to achieve or substantially achieve theacceptable input value.
 2. The apparatus of claim 1, wherein the exhaustgas system characteristic is selected from a list including a system outNOx, an exhaust flow rate, an exhaust gas temperature, a reductantdosing value, an ammonia slip value, and an ammonia storage factor. 3.The apparatus of claim 1, wherein the aftertreatment system controlcircuit is further structured to determine a NOx reduction efficiency,and compare the NOx reduction efficiency to a predetermined threshold,and wherein the acceptable input value includes an increased engine outtemperature when the NOx reduction efficiency is less than or equal tothe predetermined threshold.
 4. The apparatus of claim 1, wherein theaftertreatment system control circuit is further structured to determinea NOx reduction efficiency, and compare the NOx reduction efficiency toa predetermined threshold, and wherein the acceptable input valueincludes one of a decreased engine out temperature or an increasedengine out NOx when the NOx reduction efficiency is equal to or exceedsthe predetermined threshold.
 5. The apparatus of claim 1, wherein theaftertreatment system control circuit is further structured to determinea NOx reduction efficiency, and compare the NOx reduction efficiency toa predetermined threshold, and wherein the acceptable input valueincludes a decreased engine out NOx when the NOx reduction efficiency isless than or equal to the predetermined threshold.
 6. The apparatus ofclaim 1, wherein the exhaust gas characteristic is an ammonia slipcondition, and the aftertreatment system control circuit is furtherstructured to compare the ammonia slip condition to a predeterminedthreshold, and wherein the acceptable input value includes an increasedengine out NOx when the ammonia slip condition is equal to or exceedsthe predetermined threshold.
 7. The apparatus of claim 1, wherein theaftertreatment system control circuit is further structured to comparethe acceptable input value to a predetermined threshold criteria, andgenerate a fault code when the acceptable input value fails to meet thepredetermined threshold criteria.
 8. A system comprising: a sensorstructured to provide a sensor signal indicative of an exhaust gascharacteristic; and an aftertreatment system control circuit coupled tothe sensor, the aftertreatment system control circuit structured to:receive the sensor signal, determine an aftertreatment systemcharacteristic as a function of the exhaust gas characteristic,determine an acceptable input value as a function of the aftertreatmentsystem characteristic, and send a command signal indicative of theacceptable input value; and an engine control circuit coupled to theaftertreatment system control circuit, the engine circuit structured toreceive the command signal, and to control at least one of a fuel systemand an air handling actuator to achieve or substantially achieve theacceptable input value.
 9. The system of claim 8, wherein the exhaustgas system characteristic is selected from a list including a system outNOx, an exhaust flow rate, an exhaust gas temperature, a reductantdosing, an ammonia slip, and an ammonia storage factor.
 10. The systemof claim 8, wherein the aftertreatment system control circuit is furtherstructured to determine a NOx reduction efficiency, and compare the NOxreduction efficiency to a predetermined threshold, and wherein theacceptable input value includes an increased engine out temperature whenthe NOx reduction efficiency is less than or equal to the predeterminedthreshold.
 11. The system of claim 8, wherein the aftertreatment systemcontrol circuit is further structured to determine a NOx reductionefficiency, and compare the NOx reduction efficiency to a predeterminedthreshold, and wherein the acceptable input value includes a decreasedengine out temperature or an increased engine out NOx when the NOxreduction efficiency is equal to or exceeds the predetermined threshold.12. The system of claim 8, wherein the aftertreatment system controlcircuit is further structured to determine a NOx reduction efficiency,and compare the NOx reduction efficiency to a predetermined threshold,and wherein the acceptable input value includes a decreased engine outNOx when the NOx reduction efficiency is less than or equal to thepredetermined threshold.
 13. The system of claim 8, wherein the exhaustgas characteristic is an ammonia slip condition, and the aftertreatmentsystem control circuit is further structured to compare the ammonia slipcondition to a predetermined threshold, and wherein the acceptable inputvalue includes an increased engine out NOx when the ammonia slipcondition is equal to or exceeds the predetermined threshold.
 14. Thesystem of claim 8, wherein the engine control circuit is furtherstructured to determine a correction factor required to achieve theacceptable input value, compare the correction factor to a predeterminedthreshold, and generate a fault code when the correction factor exceedsthe predetermined threshold.
 15. A method comprising: receiving a signalfrom an aftertreatment sensor by an aftertreatment system controlcircuit, the signal indicative of an exhaust gas characteristic;determining, by the aftertreatment system control circuit, aaftertreatment system characteristic as a function of the exhaust gascharacteristic; determining, by the aftertreatment system controlcircuit, an acceptable input value as a function of the aftertreatmentsystem characteristic; communicating the acceptable input value to anengine control circuit; and controlling, by the engine control circuit,at least one of a fuel system and an air handling actuator to achievethe acceptable input value.
 16. The method of claim 15, wherein theexhaust gas system characteristic is selected from a list including asystem out NOx, an exhaust flow rate, an exhaust gas temperature, areductant dosing, an ammonia slip, and an ammonia storage factor. 17.The method of claim 15, further comprising determining, with theaftertreatment system control circuit, a NOx reduction efficiency; andcomparing the NOx reduction efficiency to a predetermined threshold, andwherein the acceptable input value includes an increased engine outtemperature when the NOx reduction efficiency is below the predeterminedthreshold.
 18. The method of claim 15, further comprising determining,with the aftertreatment system control circuit, a NOx reductionefficiency; and comparing the NOx reduction efficiency to apredetermined threshold, and wherein the acceptable input value includesa decreased engine out temperature or an increased engine out NOx whenthe NOx reduction efficiency exceeds the predetermined threshold. 19.The method of claim 15, further comprising determining, with theaftertreatment system control circuit, a NOx reduction efficiency; andcomparing the NOx reduction efficiency to a predetermined threshold, andwherein the acceptable input value includes a decreased engine out NOxwhen the NOx reduction efficiency is below the predetermined threshold.20. The method of claim 15, wherein the exhaust gas characteristic is anammonia slip condition, and the method further comprising comparing theammonia slip condition to a predetermined threshold, and wherein theacceptable input value includes an increased engine out NOx when theammonia slip condition exceeds the predetermined threshold.